The objective of this investiation is to isolate and characterize multiple DNA polymerases for normally growing cells and for cells in disease states in which growth processes are deranged. A search will be made for multiple DNA polymerases in both embryonic cells and lymphocytes from normal subjects and from patients with acute and chronic lymphocytic leukemia. By isolating and characterizing these enzymes and correlating their appearance or loss with specific DNA synthetic functions operative in the cells under various growth and functional states, it is hoped that their role in growth control will be clarified.